Does Vaccine Protect Against Omicron? Zhang Wenhong : Vaccination Booster Is Still An Effective Tool To Deal With Omicron

On May 10, an article titled "CellHost& Microbe Study: The Need for Enhanced Vaccination Against MultipleVariant Strains of Omicron" was published on the WeChat public website ofHuashan Infection.

According to the article, the team of Wenhong Zhang, director of the National Center for Infectious Diseases anddirector of the Department of Infection at Huashan Hospital, Fudan University,and Pengfei Wang's team at the School of Life Sciences, Fudan University,recently collaborated to evaluate the immune escape characteristics of foursubtypes of Omicron variant strains after two doses of inactivated vaccine anda third booster dose. People want to know that does vaccine protect againstomicron? This study further confirms that booster vaccination remains aneffective tool against omicron.

As mentioned in the article, the studyfound that subjects after two doses of inactivated vaccine had at least a5.3-fold decrease in antibody titer levels to the Omicron strain compared tothe original strain. After a third dose of homologous (inactivated vaccine) orheterologous vaccination, antibody titers increased significantly and antibodypositivity rates reached at least 75%. So, does vaccine protect againstomicron?

This study further confirms that boostervaccination remains one of the effective means to deal with omicron. Althoughthe outbreak of the Omicron strain has decreased in terms of mortality andsevere disease rates compared with the original and Delta strains, it can stilllead to increased rates of severe disease in the elderly or immunodeficientpopulation, and it is therefore important to further increase the proportion offull vaccination and booster vaccination for those who are suitable forvaccination.

Recently, the National Center forInfectious Disease Medicine, Shanghai Key Laboratory of Infectious Diseases andBiosafety Emergency Response, Prof. Wenhong Zhang's team from Huashan Infectionand Prof. Pengfei Wang's team from School of Life Sciences, Fudan Universityjointly evaluated the immune escape characteristics of four subtypes of Omicronvariant strains to two doses of inactivated vaccine and after the third boosterdose, and the related results were published on May 8 in Cell Host and Microbe(2021 IF 21.023).

As of May 2022, more than 510 million casesof novel coronavirus pneumonia have been reported worldwide.The Omicron variantof SARS-CoV-2 was first detected in November 2020 and has now become widespreadworldwide with several sub-spectra named: BA.1, BA.1.1, BA.2, BA.3, BA.4, BA.5,etc., in addition to The recombinant subtypes XD, XE, and XF strains have alsobeen detected recently. In the past 1-2 months, the proportion of BA.2 subtypeshas been rapidly increasing and has become the main prevalent strain in manyrecent outbreaks. Epidemiological studies have shown that BA.2 has now beendetected in more than 40 countries and regions, with a transmission capacityabout 30% higher than BA.1 and a viral load two times higher than BA.1 afterinfection; its subtype BA.2.12.1 contains the L452Q mutation and is detectedmore frequently in the United States and has a transmission advantage. Relatedexperiments have also studied, that does vaccine protect against omicron.

It was found that antibody titer levelsagainst the Omicron strain decreased at least 5.3-fold in subjects after twodoses of inactivated vaccine compared to the original strain. Experimental evaluationof four subtypes of pseudoviruses showed that neutralizing antibody titersagainst BA.2 were similar to or lower than BA.1. After a third dose ofhomologous (inactivated vaccine) or heterologous vaccination, antibody titersincreased significantly and antibody positivity rates reached at least 75%.Recently, three recombinant lineages (XD, XE and XF) have been reported, buttheir antibody escapes are not expected to be significantly different from thefour omicron sublineages studied because they have the same S protein as BA.1or BA.2.

Previous exploration of the neutralizingability of the Omicron BA.1 strain

In fact, in December 21, both Prof. WenhongZhang's team and Prof. Pengfei Wang's team at Huashan Infections evaluated theneutralizing ability of the Omicron BA.1 strain in serum samples from two dosesof inactivated vaccine and three doses of homozygous/heterozygous vaccination,and found that the antibody titer of the two doses of inactivated vaccineagainst the Omicron variant decreased more significantly, with the neutralizingantibody titer dropping to 6.04, an approximately 10-fold decrease compared tothe original strain. After the third booster dose of either type (inactivatedvaccine or recombinant subunit protein vaccine), serum specimens were 100%positive for neutralizing antibodies against the Omicron strain. Then, doesvaccine protect against omicron?

Scientific significance of this study

This study further confirms that thepromotion of vaccine booster injections remains one of the effective means toprevent the spread of SARS-CoV-2, especially against the Omicron strain, forthose who are suitable for vaccination. Although the outbreak of the Omicronstrain has decreased in terms of mortality and severe disease rates compared tothe original and Delta strains, it can still lead to an increase in severedisease rates in the elderly or immunodeficient populations, and therefore itis important to further increase the proportion of full vaccination and boostervaccination for those who are suitable for vaccination.